1. Bring a large pot of salted water to a boil. Cook spaghetti according to package directions until al dente, usually about 8-10 minutes. Drain and set aside, reserving 1/2 cup of pasta water.
2. While the pasta cooks, heat olive oil in a large skillet over medium-high heat. Toss the chicken pieces with Cajun seasoning until evenly coated.
3. Add the chicken to the skillet and cook for 5-7 minutes, stirring occasionally, until browned and cooked through. Remove chicken from the skillet and set aside.
4. In the same skillet, reduce heat to medium and add butter. Once melted, sauté the diced onion and sliced bell pepper until softened, about 4-5 minutes.
5. Add the minced garlic and cook for another minute until fragrant—this step always reminds me of my grandmother’s kitchen, where garlic was the secret to so many dishes.
6. Pour in the chicken broth and heavy cream, stirring to combine. Let the sauce simmer gently for 3-4 minutes to thicken slightly.
7. Gradually stir in the shredded cheddar and Parmesan cheeses until melted and the sauce is creamy and smooth. If the sauce feels too thick, add a splash of reserved pasta water to loosen it up.
8. Return the cooked chicken to the skillet, stir to coat with the sauce, and season with salt and pepper to taste.
9. Add the cooked spaghetti to the skillet, tossing gently to combine all the flavors. Warm through for 2 minutes, allowing the pasta to soak up some of the sauce.
10. Garnish with freshly chopped parsley before serving for a bright pop of color and freshness.

One little tip from my kitchen: don’t rush the sauce. Letting it simmer slowly makes all the difference in creating that luscious, creamy texture that keeps everyone coming back for seconds.